Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Hydrol. Earth Syst. Sci. Discuss., 12, 1633–1652, 2015 www.hydrol-earth-syst-sci-discuss.net/12/1633/2015/ doi:10.5194/hessd-12-1633-2015 HESSD © Author(s) 2015. CC Attribution 3.0 License. 12, 1633–1652, 2015 This discussion paper is/has been under review for the journal Hydrology and Earth System Historical changes in Sciences (HESS). Please refer to the corresponding final paper in HESS if available. frequency and seasonality of extreme floods in Historical changes in frequency and Prague seasonality of extreme floods in Prague L. Elleder L. Elleder Czech Hydrometeorological Institute, Prague, Czech Republic Title Page Received: 22 December 2014 – Accepted: 9 January 2015 – Published: 4 February 2015 Abstract Introduction Correspondence to: L. Elleder ([email protected]) Conclusions References Published by Copernicus Publications on behalf of the European Geosciences Union. Tables Figures J I J I Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion 1633 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Abstract HESSD This study presents a flood frequency analysis for the Vltava River catchment using a major profile in Prague. The estimates of peak discharges for the pre-instrumental 12, 1633–1652, 2015 period of 1118–1824 based on documentary sources were carried out using different 5 approaches. 187 flood peak discharges derived for the pre-instrumental period aug- Historical changes in mented 150 records for the instrumental period of 1825–2013. Flood selection was frequency and based on Q10 criteria. Six flood-rich periods in total were identified for 1118–2013. Re- seasonality of sults of this study correspond with similar studies published earlier for some Central extreme floods in European catchments, except for the period around 1750. Presented results indicate Prague 10 that the territory of the present Czech Republic might have experienced in the past, L. Elleder extreme floods comparable, with regard to peak discharge (POTQ10) and frequency, to the flood events recorded recently. Title Page 1 Introduction Abstract Introduction Research of historic floods significantly enhances our ability to better understand the Conclusions References 15 behaviour of recent flood events in the context of global environmental change. Numer- ous studies have focused on this issue in last two decades (e.g. Brázdil et al., 2006b; Tables Figures Glaser et al., 2010). In the Czech Republic, four extreme summer floods were recorded within the last J I 15 years (1997, 2002, 2010, and 2013). Two of these were classified as 500 year or J I 20 even 1000 year events (Hladny´ et al., 2005; Blösch et al., 2003); two out of the four stroke the Vltava River catchment. Taking into account the entire region of Central Back Close Europe, further extreme summer floods can be added: in the Alps in 2005, and in Full Screen / Esc Slovakia and Poland in 2010. An interesting question thus emerges as to whether there is an analogy with a similar frequency of important or extreme floods in the past. The Printer-friendly Version 25 aim of this contribution is to answer two scientific questions: (1) has the territory of the present Czech Republic experienced four summer extreme flood events within a mere Interactive Discussion 1634 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 15 year period earlier in history? (2) Did the region of Central Europe record extreme large-scale floods during the last 500 years more often when compared to the present? HESSD Prague is, with respect to floods, a key point for Central Europe. It represents a clos- 12, 1633–1652, 2015 ing profile of the Vltava River, the most important tributary of the Elbe River. As com- 5 pared to other major Elbe tributaries, such as the Saale, Spree, and the Elster, with respect to the catchment area, average discharge and Q100, the Vltava River can be Historical changes in regarded as the most significant one. According to the above criteria, the Vltava River frequency and is even more significant as compared to the upper part of the Elbe River, where it flows seasonality of to, 40 km downstream of Prague, at the town of M¥lník. Q100 values of the Otava and extreme floods in 10 Berounka Rivers, the most important tributaries of the Vltava River, correspond merely Prague to the Q2– Q5 levels (Table 1). Interestingly, this also applies for the Elbe River prior to the confluence with the Vltava River, which implies that the Elbe River is a tributary L. Elleder of the Vltava River rather than the other way around (Table 1). These facts are abso- lutely essential for the examination of historical floods. According to the facts above, the Title Page 15 Vltava River floods significantly influence the Elbe River floods, at least up to Torgau (before confluence with the Mulde and Saale River and Magdeburg) in Germany. There Abstract Introduction is a strong association between the peak discharges in Prague and the Elbe profiles Conclusions References in Northern Bohemia, and in Saxony – Pirna, Dresden, and Meissen (Elleder, 2013). A crucial issue for the presented study is that the flood marks and records of historic Tables Figures 20 floods (Fig. 1) going back to 1432 are available for these sites (Brázdil et al., 2005; Fügner, 2006). In this study, Prague represents the major profile, while other profiles J I were used to supplement it, and for verification of the final estimates. J I Back Close 2 Methods Full Screen / Esc 2.1 Input data Printer-friendly Version 25 For the Vltava River catchment, 159 peak discharge records for the period between 1118 and 1825, when the regular daily water level measurements began, are available Interactive Discussion 1635 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (Brázdil et al., 2005). The most reliable 18 cases, associated with summer floods, are related to the flood marks and original Prague water gauge denoted as “the Bearded HESSD Man” used since (1481 Elleder, 2004). Novotny´ (1963) presented an additional 121 12, 1633–1652, 2015 peak discharges (1825–1953) for the period before the Vltava River Cascade construc- 5 tion. The peak discharges from 1825 to 1880 were assessed earlier, with an assump- tion of the 1880–1890 rating curve validity (Richter, 1892). Water levels for Prague Historical changes in after 1954 are in the Czech Hydrometeorological Institute database, concurrently in frequency and simulation without the influence of the Vltava River dams (Ka²párek et al., 2005). seasonality of The 2012 flood, with peak discharge of 5160 m3 s−1, is the most important case extreme floods in 10 over the instrumental period (Hladny´ et al., 2005). Interestingly, the flood of July 1432 Prague was likely even more important (Elleder, 2010; Da¬helka, 2012). For other significant L. Elleder historic floods – bigger than Q50 – in the Vltava River catchment, Brázdil et al. (2005) published brief descriptions. Detailed papers, though most of them only in Czech, were published for the following floods: 1432 (Da¬helka, 2012), 1582 (Elleder and Kotyza, Title Page 15 2007), 1714 (Elleder et al., 2014), 1784 (Munzar et al., 2014), 1830 (Munzar, 2000), 1845 (Kakos and Kulasová, 1995), 1862 (Elleder et al., 2012b), 1872 (Elleder et al., Abstract Introduction 2012a), and the 1890 (Kakos, 1990). Regretfully, the extreme flood cases, such as Conclusions References 1501, 1598, 1655, 1675, 1799, and 1824, have not been evaluated so far. For archiving of documentary sources related to floods over the Czech territory, the author has been Tables Figures 20 developing a private relation database system “Krolmus” since 2000. J I 2.2 Major Vltava River profile in Prague and its changes over time J I The major Vltava River profile for Prague until 1825 was the monastery of the Knights Back Close with Red Star past the Charles Bridge; after 1825 with the beginning of the systematic water level measurements it was the Old Town Mills profile before the Charles Bridge. Full Screen / Esc 25 The entire period under review, 1118–2013, has been divided into seven periods (P1– P7), with respect both to the reliability of input data and changes in the area near Printer-friendly Version the major profile. The least reliable data are these relating to 1118–1350 (P1). After Interactive Discussion the construction of the new town walls (1250–1300) and reconstruction of the city, 1636 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | the Old Town terrain was more or less stabilized (Hrdli£ka, 2001). In 1351–1480 (P2) some floods are recorded as related to important town buildings (Table 2). During this HESSD period, the number and height of Prague weirs were fixed. In 1481–1780 (P3) the 12, 1633–1652, 2015 records of water levels are available. Since 1481 these are related to the “Bearded 5 Man” water gauge (Elleder, 2004, 2012). Since 1501 flood marks started to appear, but those from 1501 and 1655 were destroyed, and currently flood marks since 1675 are Historical changes in preserved (Brázdil et al., 2005). Changes between the 16th and the mid19th century frequency and were minor (Elleder et al., 2012). The first modern water gauge in Prague was set up seasonality of in 1781 (Brázdil et al., 2005; Elleder, 2010). Systematic records date back to 1825. extreme floods in 10 The next 60 year period of 1781–1843 (P4) until the construction of the Vltava River Prague embankment is used for calibration of the relation between measured water stages during flood events and flood impacts, such as the flooded area (Elleder, 2010). For the L. Elleder next period of 1844–1909 (P5), when the Vltava River embankment construction was undertaken, a rating curve is available. In 1910–1926 (P6a) the inundated area of the Title Page 15 Old Town was raised to the embankment.